1. Field of the Invention
This invention relates to a vacuum plasma treatment apparatus which may be used for various treatments such as etching, formation of a deposition film, cleaning and the like.
2. Description of the Prior Art
As an electric insulating material for a vapor phase method treatment apparatus using gas plasma, the material which is chemically and thermally stable and which releases gas as little as possible under vacuum condition is desired.
As an electric insulating material used as a member constituting a vacuum treatment apparatus for fabricating a semiconductor device, it is essential that the material has an airtight property such that a leak does not occur.
Accordingly, the electric insulating material for the vacuum treatment apparatus in which high vacuum is required for fabricating a semiconductor or the like is generally a quartz (SiO.sub.2) ceramic.
In the vapor phase method treatment apparatus, also, quartz ceramics are often used as the material constituting a gas-releasing pipe for supplying a starting gas for formation of a film under the plasma atmosphere, a window, and a reaction chamber, let alone an insulator.
However, in the case where a silicon wafer is etched and patterned using a chlorocarbon or fluorocarbon type gas such as CF.sub.4 and the like as an etching gas in the vacuum treatment apparatus using these quartz ceramics, the surface of the material comprising the quartz ceramic exposed to the plasma atmosphere will be corroded by a fluorine radical or the like formed in the plasma.
This corrosion is carried on by chemical reactions between silicon as a construction element of the quartz ceramics and the fluorine radical from the plasma and the consequent production of silicon tetrafluoride (SiF.sub.4).
Such corrosion in the vapor phase method treatment apparatus causes undesirable etching by adhesion of corrosion powder onto an etching-receiving surface as well as problems in capacity of the apparatus such as a lowering of electric insulating property of the insulator, a gas leak from a gas releasing pipe, a lowering of translucent property of the material constituting the window, a lowering of a vacuum degree by the leak and the like.
Some of the conventional apparatuses utilize an organic compound such as polytetrafluoroethylene and the like, in which case there also arises the problem of the change in shape due to the corrosion, as is the case with quartz ceramics.